Chapter 7Chapter 7

Chemical Names and Chemical Names and FormulasFormulas

Molecules and Molecular Compounds

•Molecule – the smallest electrically neutral unit of a substance that still has the properties of a substance.

•Molecular Compounds – Compounds composed of molecules.

Ions

• Ions – atoms or groups of atoms that have a positive or negative charge.– Ions form when an atom or group of atoms gains or loses an electron.•There are two different types of ions: anions and cations.

•Cation – any atom or group of atoms that has a positive charge.– Ex Sodium is a cation because

it has 11 protons and only 10 electrons. Sodium has a charge of 1+

•Na 1+ = Na+

(the number 1 is usually omitted)

Cations

• Anions – atoms or groups of atoms with a negative charge– Ex Chloride is an anion

because it has only 17 protons and 18 electrons.

Chloride has a charge of 1-

-- Cl 1- = Cl-

Anions

More Examples!

Cations Symbol Anions Symbol

Aluminum Al3+ Chlorate ClO3-

Cobalt(II) Co2+ Fluoride F-

Lead (IV) Pb4+ Hydroxide OH-

Magnesium Mg2+ Nitride N3-

Mercury (II) Hg 2+ Oxide O2-

Potassium K + Peroxide O22-

• Ionic compounds are composed of cations and anions–They are usually composed of a metal cation and a non-metal anion• Ex – Sodium Chloride

–sodium cation & chloride anion

Ionic Compounds

Chemical Compounds

•Chemical Formula – shows the kinds & numbers of atoms in the smallest representative unit of the substance.

Diatomic Compounds• They are non metallic elements

– Remember them!!!!! ( all 7 )•Hydrogen H2

•Fluorine F2

•Oxygen O2

•Nitrogen N2

•Chlorine Cl2

•Bromine Br2

•Iodine I2

• Molecular Formulas show the kinds and numbers of atoms present in the molecule of a compound.– Ex Ammonia = NH3

H N H

H

Molecular Formulas

**This structural formula shows that Ammonia has 3 atoms of Hydrogen and 1 atom of Nitrogen

Formula Units

•Formula Units represent the lowest whole number ratio of ions in a compound.– Ex Sodium Chloride

•1 Na+ to each Cl-

•The ratio of ions is 1:1• NaCl

• Magnesium Chloride– Contains magnesium cations (Mg2+) and

chloride anions (Cl-)– Ratio is 1:2

– Mg 2+ Cl –

-- MgCl2

More Examples and Forming Compounds….

•Aluminum Chloride• Contains aluminum cations

(Al3+) and chloride anions (Cl-)• Ratio is 1:3

Al 3+ Cl -

-- AlCl3

Type I Binary Ionic

• Group “A” metal – non metal– Name of metal + name of non metal +ide

– Ex – NaCl – Sodium Chloride

– CaBr2 – Calcium Bromide

– Al2O3 – Aluminum Oxide

•Transition Metal – non metal–Name of metal + Roman Numeral + Non Metal + ide•Exceptions ( Ag+, Zn2+, Cd2+)•Ex

•Cu2O – Copper(I) Oxide

•HgI2 – Mercury (II) Iodide

Type II Ternary Ionic

• Group “A” Metal-Radical–name of metal + name of radical

• Transition Metal-Radical–name of metal+ Roman Numeral+ name of radical

•Non Metal – Non Metal•Use Prefixes

–Mono - Hexa–Di - Hepta–Tri - Octa–Tetra - Nona–Penta - Deca

–Ex PCl 3 - Phosphorous Tri Chloride

SF6 - Sulfur Hexa Flouride

Acids

•Give off H+ ions when dissolved in H2O

•Acids in form of HX

•where X = mono-atomic or poly-atomic ions

3 Rules1) If X ends in - ide , acid

name begins with the prefix hydro, and the stem of the anion has the suffix - ic followed by the word acid.Ex: HCl X =

Chloride Hydrochloric Acid

•2) If X ends in -ite , the acid name is the stem of the anion with the suffix -ous , followed by the word acid.

–Ex: H2SO3 X= Sulfite

»Sulfurous Acid

•3) If X ends in - ate, the acid name is the stem of the anion with the suffix - ic, followed by the word acid.

–Ex: HNO3 X= Nitrate

»Nitric Acid

Examples

•HClO3 - Chloric Acid

•HCN - Hydrocyanic Acid

•H3PO4 - Phosphoric Acid

•HF - Hydroflouric Acid

•HC2H3O2 -Acetic Acid

More Examples

•H2SO4 - Sulfuric Acid

•HNO2 - Nitrous Acid

•Hydroiodic Acid - HI

•Chromic Acid - H2CrO4

•Chlorous Acid - HClO2